text: This variant integrates the membrane unit directly into the bioreactor unit. This configuration varies from the other two in the fact that the raw influent enters the membrane unit instead of first going through the anaerobic process. In the membrane unit, a low negative pressure separates the retentate and permeate. The permeate, otherwise known as the effluent, leaves the system while the retentate goes through the anaerobic process to become biogas.